Fluorinated organomercury compounds



United States Patent Oflice 3,419,590 Patented Dec. 31, 1968 ABSTRACT OF THE DISCLOSURE Fluorinated organomercury compounds, useful in the construction of floated control instruments, have the formulae:

F HgR F HgR1 and F2 lfIgRa F2 wherein R is selected from the group consisting of CH -CF=CF and R is selected from the group consisting of -CH and R is selected from the group consisting of CH --CF=CF and and X is selected from the group consisting of chlorine, bromine, fluorine and -HgCH This invention relates to floated control instruments in which the flotation fluid is a fluorinated organomercury compound.

In a floated gyroscope the rotor is encased in a float suspended in a fluid, the density of which is chosen to correspond to that of the float. Such an arrangement makes for exceedingly low pivot-friction since the float is supported almost completely by pressure gradients in the fluid. Moreover, the gyro fluid protects the assembly from shock, provides a damping function and serves as a heat transfer medium to dissipate heat developed by the rotor. Where the damping effect on the precession of the float is largely developed by the fluid itself a fluid is generally selected having a high viscosity. However, where damping is not desired or where electronic or orifice damping is employed low viscosity liquids are preferred.

In addition to the above described uses in a single gyroscope, a gyro fluid may be used in a system wherein one or more gyros and associated equipment are mounted on a platform which is floated in the fluid. For this application the fluid is usually a dense, low viscosity liquid.

The liquids which are useful in gyroscopes must have certain critical physical characteristics. High density is required-at least about 1.6 g./ml. The greater the density the more useful the fluid since this permits more inertia to be built into the rotor without imposing higher loads on the pivot. A higher density fluid allows size reduction at the same amount of inertia (and sensitivity of the gyro). A second requirement of such liquids is Newtonian be havior, i.e,. the viscosity is independent of the shearing rate. Preferably, the liquid should be relatively insensitive in viscosity to temperature variations. The latter property enables the fluid to remain useful over the operational temperature range of the gyroscope.

Finally, it is essential that the liquid exhibit chemical stability under the operating conditions of the gyroscope since any degradation or breakdown products would very likely cause corrosion of the gyroscope parts.

It is extremely diflicult to find a fluid possessing the aforedeliniated requirements. Fluids in general use today are based on fluorocarbons because of the known stabilizing effect of large numbers of fluorine atoms on halogenated carbon compounds. The high viscosity fluids are generally telomers of CFC1=CF and of CFBr=CF having densities in the range of about 1.7 g/ml. to about 2.4 g./ml., respectively. Where low viscosity liquids are required, low molecular weight ends of the telomerization product of the olefins are sometimes employed; a volatile fluorinated cycloether having the empirical C F O and a density of 1.7602 g./ml. at 25 C. is also in common use. Halogenated hydrocarbons other than fluorinated hydrocarbons have proven to be more or less sensitive to hydrolysis and thermal decomposition thereby forming hydrohalic acids and/or free halogens which are highly corrosive to certain metal parts in the gyroscope.

It has now been discovered that certain novel organomercury compounds having a substantial degree of fluorine substitution serve as excellent gyro fluids and the provision of the aforesaid compounds and their use as gyro fluids constitute the principal objects and purposes of the invention. Other objects and purposes will be made manifest subsequently.

The novel fluorinated organomercury compounds herein are disubstituted organic mercury compounds characterized in that at least one of the organic substituents is a lower cycloalkenyl group having a substantial degree of fluorination. The configuration of the: compounds is more readily visualized by reference to the following formulae:

(I) F HgR F Cl F 0 Cl and (III) F2 Hg R2 wherein R represents -CH CF=CF R represents CH CF=CF R represents CH CF=CF and and where Z completes the fluorocycloalkene nuclei of Formulae I, II and III, M is an organometallic residue such as an alkyllithium or RMgX where R is lower alkyl and X is chlorine, bromine or iodine and R has the values R, R and R defined elsewhere herein except where R contains a carbon-mercury bond such as In these instances the R M is not formed from the organometallic reagent since the latter may cleave the mercury-carbon bond. Where R contains HgCH such 4 the methylmercuritetrafluorophenylcycloalkylmercury. is prepared by an alternate route as illustrated by the following equations:

HgCH a HgCl-l s a F4 M F4 @HgBr E2 HE;

$01.13 01 HgCH B2 In general, the reactions are carried out by combining stoichiometric amounts of components in the presence of an inert, normally liquid organic solvent such as diethyl ether. It is preferable to conduct the reactions under an inert atmosphere such as dry nitrogen. The temperature should be less than room temperature, preferably about 0 C.

The requisite fluorinated l-bromocycloalkene intermediates are obtained using a procedure patterned after that of J. D. Park et al., J. Org. Chem., 29, 3664 (1964). One of the intermediates, 1-bromo-2-chloro-3,3,4,4,5,5- hexafluorocyclopentene has not previously been synthesized.

The fluorinated organomercury compounds are unusual in that they possess high density-of the order of 2.7 g./nil.while being remarkably stable. It is these dual properties which make them especially suitable for use as gyro fluids.

Reference is now made to the following non-limited examples.

Example l.-2,3-dichloro-3,4,4-trifiuoro-l-cyclobutenyl- (A) Preparation of 2,3-dichloro-3,4,4-trifluoro-l-cyclobutenylmercuric chloride.

Into a 250 ml., three neck flask previously flame dried and swept out with nitrogen and equipped with a thermometer, a pressure equilibrated addition funnel, a condenser with drying tube and a magnetic stirrer is charged 0.973 g. (0.04 mole) of magnesium (99.99% purity) and 10 ml. of dry ether. A solution of 4.5 g. (0.041 mole) of redistilled ethyl bromide in 30 ml. of dry ether is then added at such a rate as to sustain gentle refluxing of the flask contents. The reaction is refluxed 1 /2 hours longer after which a few drops of ethyl bromide is added to react with any residual magnesium. The resulting Grignard reagent is cooled to 0 C. and so maintained while adding dropwise thereto a solution of 8.96 g. (0.035 mole) of l bromo 2,3-dichloro-3,4,4-trifluoro-1-cyclobutene in ml. of dry ether. After stirring for 30 minutes at 0 C., 9.0 g. (0.033 mole) of solid mercuric chloride is added in portions, keeping the temperature near 0 C. In about one hour the mercuric chloride dissolves. Stirring is continued one-half hour longer. At this point formation of the 2,3-dichloro-3,4,4-trifiuoro-l-cyclobutenylmercuric chloride is essentially complete. It can either be isolated or transformed in situ to the desired diorganomercury derivative. Isolation is carried out as follows.

Water is added to the completed reaction mixture and the precipitated solids filtered off and Washed with a large volume of ether. The filtrate is washed with 20 ml. of cold water, dried over anhydrous magnesium sulfate and evaporated to dryness. The 2,3-dichloro-3,4,4-tri- Example 2 F HgC F=C F,

Cl F Cl From the appropriate chloromercuri derivative of 1- bromo-2,3-dichloro-3,4,4-trifluoro-l-cyclobutene and trifluorovinyllithium.

Example 3 F F F Q or or F F From the appropriate chloromercuri derivative of 1- bromo-2,3-dichloro-3,4,4-trifluoro-l-cyclobutene and pen tafiuorophenyllithium.

Example 4 H orn F F2 Cl From the appropriate chloromercuri derivative of 1- bromo-2-chloro-3,3,4,4,5,5-hexafluoro-l-cyclopentene and methyllithium.

Example 5 From the appropriate chloromercuri derivative of 1- bromo-2-chloro-3,3,4,4,5,5-hexafluoro-l-cyclopentene and trifluorovinyllithium.

Example 6 F2 F F N 61 From the appropriate chloromercuri derivative of 1- bromo-2-chloro-3,3,4,4,5,5-hexafluoro-l-cyclopentene and pentafluorophenyllithium.

Example 7 F HgCHs Fromthe appropriate chloromercuri derivative of 1- bromo 2 chloro 3,3,4,4-tetrafluoro-l-cyclobutene and methyllithium.

Example 8 F HgC F=C F 2 From the appropriate chloromercuri derivative of 1- bromo-2-chloro-3,3,4,4-tetrafluoro-l-cyclobutene and trifluorovinyllithium.

6 Example 9 F F F Q F m r F From the appropriate chloromercuri derivative of 1- bromo-2-chloro-3,3,4,4-tetrafluoro-l-cyclobutene and pentafiuorophenyllithium.

As will be apparent to those skilled in the art, numerous modifications and variations of the formulation of the gyro flotation fluids illustrated above may be made without departing from the spirit of this invention or the scope of the following claims.

We claim:

1. A fluorinated organomercury compound selected from the class consisting of F2 HER I CI Fr HgRi F 0 Cl and --HgR2 F2 F2 Cl wherein R is selected from the group consisting of CH;;, OF=CF '|F2 Cl FOl and R is selected from the group consisting of -CH;;, --CF=CF and R is selected from the group consisting of CH and X is selected from the group consisting of chlorine, bromine, fluorine and --HgCH 2. A fiuorinated organomercury compound of claim 1 wherein the compound is F HgOHa 3. A fluorinated organomercury compound of claim 1 wherein the compound is 3,419,590 7 8 A 4. A fluorinated organomercury compound of claim 1 8. A fluorinated organomercury compound of claim 1 wherein the compound is wherein the compound is F HgCHa 9. A fiuorinated organomercury compound of claim 1 wherein the compound is "-H CF=CF 5. A fluorinated organomercury compound of claim 1 g wherein the compound is 10 I 10. A fluorinated organomercury compound of claim 1 wherein the compound is F F 15 Q 6. A fluorin'ated organomercury compound of claim 1 F F wherein the compound is F 01 References Cited F2 HECF=CF2 F2 UNITED STATES PATENTS F 01 2,675,400 4/ 1954 Howard 260-431 2 3,156,715 11/1964 Haszeldine et a1 260-433 4 3,244,749 4/1966 Wei] 260-431 XR 7. A fluormated organomercury compound of claim 1 25 3,250,795 5/1966 Cotrafke 260433 wherein the compound is TOBIAS E. LEVOW, Primary Examiner.

gQ H. M. S. SNEED, Assistant Examiner. F2

F F 30 US. Cl. X.R. 

